U.S. patent number 6,208,242 [Application Number 09/529,920] was granted by the patent office on 2001-03-27 for circuit configuration to monitor a regulated output voltage in a motor vehicle.
This patent grant is currently assigned to Continental Teves AG & Co., OHG. Invention is credited to Mario Engelmann, Wolfgang Fey, Micha Heinz, Michael Zydeck.
United States Patent |
6,208,242 |
Engelmann , et al. |
March 27, 2001 |
Circuit configuration to monitor a regulated output voltage in a
motor vehicle
Abstract
The present invention relates to a circuit arrangement to
monitor a regulated output voltage in an automotive vehicle,
wherein the regulated output voltage is monitored as to whether
defined threshold values have been exceeded and/or have fallen
short of, wherein the circuit element for regulating the output
voltage and the circuit element to monitor whether threshold values
have been exceeded or have fallen short of are integrated in one
chip, wherein the adjustment of the output voltage is effected by
way of a first reference voltage, and wherein monitoring of the
threshold values as to whether they have been exceeded or have
fallen short of is conducted by way of a second reference
voltage.
Inventors: |
Engelmann; Mario (Steinbach,
DE), Heinz; Micha (Darmstadt, DE), Fey;
Wolfgang (Niedernhausen, DE), Zydeck; Michael
(Langgons, DE) |
Assignee: |
Continental Teves AG & Co.,
OHG (Frankfurt, DE)
|
Family
ID: |
26041062 |
Appl.
No.: |
09/529,920 |
Filed: |
June 23, 2000 |
PCT
Filed: |
October 22, 1998 |
PCT No.: |
PCT/EP98/06726 |
371
Date: |
June 23, 2000 |
102(e)
Date: |
June 23, 2000 |
PCT
Pub. No.: |
WO99/21745 |
PCT
Pub. Date: |
May 06, 1999 |
Foreign Application Priority Data
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|
|
Oct 24, 1997 [DE] |
|
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197 47 014 |
Nov 20, 1997 [DE] |
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197 51 429 |
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Current U.S.
Class: |
340/438; 318/563;
340/660; 340/661; 340/662 |
Current CPC
Class: |
B60T
8/885 (20130101); G01R 19/16538 (20130101); G01R
31/007 (20130101); B60T 2270/414 (20130101) |
Current International
Class: |
B60T
8/88 (20060101); G01R 19/165 (20060101); G01R
31/00 (20060101); B60Q 001/00 () |
Field of
Search: |
;340/438,660,661,662,663
;318/563 ;327/393 |
References Cited
[Referenced By]
U.S. Patent Documents
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|
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4428020 |
January 1984 |
Blanchard, Jr. |
4546437 |
October 1985 |
Bleckmann et al. |
5144248 |
September 1992 |
Alexandres et al. |
5648759 |
July 1997 |
Miller et al. |
5805061 |
September 1998 |
Fritz et al. |
5880568 |
March 1999 |
Bederne et al. |
5955910 |
September 1999 |
Levin et al. |
|
Primary Examiner: Wu; Daniel J.
Assistant Examiner: Nguyen; Phung T
Attorney, Agent or Firm: Rader, Fishman & Grauer
PLLC
Claims
What is claimed is:
1. Circuit arrangement for monitoring a regulated output voltage in
an automotive vehicle, comprising:
an integrated circuit including
a first voltage reference,
a first voltage regulator coupled to said first voltage
reference,
a first comparator, coupled to both the first voltage reference and
the first voltage regulator, for determining if a first threshold
has been exceeded, and sending a reset signal,
a second voltage reference spatially, mechanically, and
electrically independent from said first voltage reference,
a second comparator, coupled to both the second voltage reference
and the first voltage regulator, for determining if a second
threshold has been exceeded, and sending an output signal
indicating that the second threshold has been exceeded.
2. Circuit arrangement as claimed in claim 1, wherein said
integrated circuit further includes:
an oscillator circuit, and
a watch dog timer, wherein the frequency of oscillation of said
oscillation circuit is determined, at least in part, by said second
voltage reference.
3. Circuit arrangement as claimed in claim 2, further including
means, coupled to output signal of said second comparator, for
disabling a main driver stage.
4. Circuit arrangement as claimed in claim 3, further including a
driver stage coupled to said output signal of said second
comparator for switching on alarm lamps.
5. Circuit arrangement as claimed in claim 2, further including a
microprocessor coupled to said reset signal.
Description
TECHNICAL FIELD
The present invention relates to a circuit arrangement to monitor a
regulated output voltage in an automotive vehicle.
BACKGROUND OF THE INVENTION
Electric and electronic components in an automotive vehicle which
are operated, or actuated under certain circumstances, by means of
an electric voltage may be destroyed when they are acted upon by a
too low or too high voltage. In order to compensate for voltage
variations in the electrical system of an automotive vehicle, it is
known in the art to make available a regulated output voltage and
to monitor the level of the output voltage by means of a
comparator. With this regulated output voltage, the voltage of the
electrical system is adjusted to a defined value by way of a
reference voltage.
Where the objective is to integrate the circuit element for
generating the regulated output voltage with other circuit elements
jointly in one chip, another problem involves the possible
destruction of the chip itself due to a wrong output voltage.
This is critical especially in systems which are important for
driving safety because, in case of an error, a proper disconnection
of the system must be ensured in order to permit activation of a
defined emergency operation mode. This applies to ABS/TC (traction
slip control) systems, for example.
U.S. Pat. No. 5,648,759 A describes a circuit arrangement for
voltage monitoring wherein two reference voltages are used. The
first reference voltage is used to regulate the output voltage.
The output voltage is monitored by means of a second reference
voltage or a voltage zone between a top limit value and a bottom
limit value. Both reference voltages are taken from one single
electronic reference voltage source.
Therefore, an object of the present invention is to increase the
fail safety of systems of this type.
According to the present invention, this object is achieved by the
circuit arrangement of the present invention, wherein the circuit
element for regulating the output voltage and the circuit element
to monitor whether threshold values have been exceeded or have
fallen short of are integrated in one chip, and wherein further the
adjustment of the output voltage is effected by way of a first
reference voltage, and wherein monitoring of the threshold values
as to whether they have been exceeded or have fallen short of is
conducted by way of a second reference voltage.
Advantageously, this improves the reliability in detection of an
error. It can be detected when any one of the two reference
voltages adopts wrong values. In case the first reference voltage
is incorrect, there will occur a wrong regulated output voltage,
corresponding to the incorrect first reference voltage, which can
be detected by means of the second reference voltage. It is then
possible to perform error handling when a discrepancy between the
regulated output voltage and the second reference voltage is
detected. In case the second reference voltage is incorrect,
admittedly, the regulated voltage will still adopt the correct
values. However, there will nevertheless occur a difference between
the regulated output voltage and the second reference voltage, for
what reason error handling is carried out also in this case.
This proves favorable compared to a circuit arrangement wherein the
regulated output voltage is produced with the same reference
voltage which is used to check in a comparator whether the
regulated output voltage has adopted the correct value. In case the
reference voltage drifts away, the thresholds of the comparator
will change in the same sense as the regulated output voltage so
that the error will not be noticed. In the present case of
application described herein, this may be especially critical for
the reasons indicated above. Thus, fail safety will be increased
because an error case can be detected before components, in
particular components which are critical under safety aspects, will
possibly be destroyed.
It is especially advantageous when also the driver stages for the
consumers, such as the valve drivers in an ABS/TC system, are
jointly integrated in the chip.
In a preferred embodiment of the circuit arrangement, the first
reference voltage is used in order to check the regulated output
voltage.
This permits detecting, for example, whether the voltage regulation
operates incorrectly with a correctly predetermined first reference
voltage. This provision permits further improvement of the
detection of potential errors and, hence, further enhancement of
the fail safety of this system.
Preferably, another electronic circuit is supplied with the output
voltage, and this circuit is monitored by means of a watchdog
circuit element integrated in the chip of the circuit arrangement,
with the oscillator of the watchdog circuit element being supplied
with the second reference voltage.
It may be ensured by this embodiment in particular that the further
electronic circuit is checked in the circuit arrangement by making
use of the second reference voltage. This means if an incorrect
voltage is supplied to the further electronic circuit due to an
incorrect first reference voltage, this circumstance can be
detected in the signals sent by the further electronic circuit to
the watchdog circuit. In case no more signals are sent, this will
of course be detected by the watchdog circuit as well.
When an error is detected by the watchdog circuit element, driver
stages for external consumers will be disconnected in the
embodiment of the circuit arrangement according to claim 4.
This proves especially favorable when these driver stages are
integrated in the chip. Destruction of the chip is reliably
prevented due to this provision. Also, it is possible to switch the
system over into an emergency operating mode.
Still, in another embodiment a driver stage to switch on alarm
lamps is activated when an error is detected by the watchdog
circuit element.
This makes it easy to recognize an error and a consequent
disconnection of the system.
Further, checking of the output voltage by means of the first
reference voltage is carried out by a comparator which is
integrated in the chip of the circuit arrangement, and the
microprocessor is reset as soon as the comparator detects that a
defined threshold value has been exceeded or has fallen short
of.
This renders it possible in a simple fashion to conduct a checking
operation with the first reference voltage without increased
circuit structure. When this first reference voltage, in the
capacity of a comparison voltage with regard to the regulated
output voltage, is applied to the input of the comparator, and the
output of the comparator is applied to a reset input of the
microprocessor, the microprocessor will be reset as soon as the
comparator detects an inadmissible difference between the regulated
output voltage and the first reference voltage. The microprocessor
is then reset by way of the reset input of the microprocessor.
Signals are no longer sent to the watchdog circuit element due to
this reset of the microprocessor so that a case of error is
detected by the watchdog circuit element of the circuit
arrangement. This watchdog circuit element (furnished with the
second reference voltage) is used to initiate the respective
further measures, such as the disconnection of the driver stages of
consumers and the activation of a driver for actuating alarm
lamps.
This means that detection of an error situation with a deactivation
of the system (reset of the microprocessor, deactivation of
consumers) can be performed with little circuit structure
needed.
In yet another embodiment, the output voltage of the controller is
supplied to an input of a comparator whose other input is furnished
with the second reference voltage, and it is monitored by means of
the comparator whether a defined threshold value of the output
voltage has been exceeded or has fallen short of.
The result is that the level of the output voltage is directly
compared to the second reference voltage.
Driver stages for external consumers are disconnected when a
comparator detects that the defined threshold value has been
exceeded or has fallen short of.
This proves particularly favorable when these driver stages are
integrated in the chip. Destruction of the chip is reliably
prevented by this measure. Besides, the system can be switched over
into an emergency operating code.
Preferably, a driver stage for switching on alarm lamps is
activated when a comparator detects that the defined threshold
value has been exceeded or has fallen short of.
This permits easily recognizing an error and disconnection of the
system caused thereby.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic representation of a circuit arrangement 1 for
monitoring a regulated output voltage in an automotive vehicle.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now referring to FIG. 1, circuit arrangement 1 shown is employed in
an ABS/TC system. Two reference voltages 2 and 4 which are
independent of each other are available in the circuit arrangement.
A circuit element 3 of the circuit arrangement 1 comprises a
voltage regulator which is supplied with the voltage of the
electrical system of the automotive vehicle by way of connection 5
of the circuit arrangement 1 and, further, with the reference
voltage corresponding to block 2 in the block diagram of this
Figure. At connection 6, the circuit element 3 emits the regulated
output voltage which is available internally in the circuit
arrangement 1 and for the voltage supply of external
appliances.
The first reference voltage corresponding to block 2 and the
regulated output voltage of output 6 of the circuit element 3 is
sent to a comparator 7. When the comparator 7 detects an excessive
difference between its two input voltages, reset of a
microprocessor 8 is carried out by way of the output of comparator
7 by sending a corresponding output signal of comparator 7 to an
input of microprocessor 8. Microprocessor 8 represents another
electronic circuit which is monitored by the circuit arrangement.
The circuit arrangement 1 includes a watchdog circuit element 9 for
this purpose. Corresponding to the illustration of the connection
10, signals are sent from the microprocessor 8 to the circuit
arrangement 1 by which a potential error of the microprocessor 8
shall be detected. Thus, when microprocessor 8 is reset, signals
are no longer emitted by way of connection 10 which the watchdog
circuit element 9 identifies as an error.
The second reference voltage 4 is applied to oscillator 11 of the
watchdog circuit element 9 in order to generate the oscillation
frequency of the watchdog circuit element 9. Further, another
comparator 12 is supplied with the regulated output voltage by way
of output 6 of the circuit element 3 and also with the second
reference voltage corresponding to block 4. When the comparator 12
detects an excessive difference between the two input voltages, a
corresponding signal is emitted by way of output 13 of comparator
12 which serves to disconnect the main driver 14 and the valve
driver outputs 15 of the valves in the brake system of the
automotive vehicle equipped with an ABS/TC system. There is further
provision of a driver 16 which is activated when this signal
appears so that the corresponding alarm lamps are actuated.
Those parts of the circuit arrangement 1 integrated in a chip which
are supplied by the circuit element 3, are resistant to
overvoltages so that a reliable disconnection of the controller is
ensured even if the voltage regulators fail.
Also, the drivers are actuated when an error is detected by the
watchdog circuit element 9. As described hereinabove, this can
occur when the signals sent by the microprocessor 8 will change or
when the second reference voltage changes because these conditions,
too, will cause a change in the clock rate of the watchdog circuit
element 9 which, in turn, is interpreted as an error.
To ensure a reliable actuation of the alarm lamps in an error case,
the alarm lamps are completely independent of the voltage
references.
The voltage regulator and voltage monitoring have no
interdependencies. This is achieved by the provision of two voltage
references in the chip which are completely independent of each
other in spatial, mechanical and electrical respects.
Advantageously, the second reference voltage can still be used to
generate the reference currents for the current limitation of the
valves.
Thus, a circuit arrangement of the above type permits integration
of the voltage regulator 3, valve driver 15 and charging pump 14
for the actuation of the semiconductor main relay in one chip, with
sufficient safety in the error case.
* * * * *